New insights into the pain of knee osteoarthritis: the characteristics of deep pain and abnormal central processing.

Knee osteoarthritis (KOA) represents one of the most common causes of chronic pain. The high prevalence and disability rates of KOA impose a severe burden on both individuals and society. In contrast to cutaneous pain, KOA-induced joint pain is characterized as a deep tissue pain that potentially involves distinct subgroups of peripheral sensory neurons and central processing mechanisms. Furthermore, KOA pain is closely related to locomotion activity. Impaired sensorimotor integration and pain mutually reinforce each other in KOA, forming a vicious cycle that exacerbates disease progression. In this review, we highlight the key differences between KOA pain and cutaneous pain, and the latter has been extensively studied in the pain field. We hope to offer new insights into the central mechanisms and development of new treatment strategies for KOA based on the interactions between impaired sensorimotor integration and chronic joint pain.